An administrative law judge is expected to issue a ruling early next week on whether there’s enough evidence to conclude Arizona Attorney General Tom Horne illegally coordinated campaign spending with an aide running an independent group during his 2010 campaign.

Yavapai County prosecutors say they showed during a civil hearing in February that Horne and aide Kathleen Winn broke campaign-finance law by working together on outside ads targeting Horne’s Democratic opponent in the weeks before the November 2010 election won by the Republican attorney general. They want Horne to repay $400,000 to donors and up to three times that amount in civil fines.

Lawyers for Horne and Winn said there is no evidence the pair broke campaign finance laws. They also argued that an FBI agent who investigated the case committed perjury.

Horne himself testified that he “absolutely never” had illegal communications with Winn, an aide who was leader the independent campaign backing him during his 2010 election bid.

“We absolutely never coordinated or violated any of the laws,” he said. “I absolutely never did coordinate with Kathleen Winn.”

Judge Tammy Eigenheer of the Arizona Office of Administrative Hearings oversaw three days of testimony in February. Attorneys had expected her ruling Thursday, but she has now set the deadline for Monday.

The decision will likely not be the end of the case, however, because Yavapai County Attorney Sheila Polk can accept or reject her findings and impose sanctions herself. Polk determined in October that Horne violated the law and ordered the repayments and the filing of amended campaign-finance reports.

Horne and Winn could appeal any decision, dragging any final conclusion into the election season, where Horne faces a challenger in August’s Republican primary as he seeks a second term. If he wins the primary, he’ll likely face the same Democrat he narrowly defeated in 2010, Felecia Rotellini, a former prosecutor and bank regulator.

Horne and Winn are accused of working together on a campaign ad targeting Rotellini that was paid for by an independent group Winn was running, Business Leaders for Arizona. Such coordination would be illegal in Arizona.

But lawyers for Horne and Winn argued during the hearing and in court filings that prosecutors came up woefully short of proving their case. Horne’s lawyer, Michael Kimerer, wrote that the five examples prosecutors point to as providing evidence of illegal coordination made no sense, and that they did not show that there was substantial discussion connected with the ad attacking Rotellini. Prosecutors needed to show “clear and convincing” evidence of a violation, and they did not, he said.

One of Winn’s lawyers, Timothy La Sota, wrote that the case presented by the Yavapai County attorney’s office is nothing but “speculation” and “bottomless inference.”

“They were not a party to the conversations between Horne and Winn, they don’t have a witness who was, and the witness they do have tells us that YCAO’s theory actually doesn’t make sense,” La Sota wrote in a March filing. “They speculate as to what the parties talked about and call this an ‘inference.’ “

Prosecutors counter that there is a “preponderance of evidence” showing that Horne and Winn spoke about the ad and Horne urged her to raise additional money for it to be aired in the days before the election. That’s a lower standard than the defense wants Eigenheer to adopt. They say in a court filing that Winn spoke to Tom Horne by phone several times on Oct. 20, 2012, the same day Winn exchanged emails with her campaign consultant about the content of the ad. The timing of the calls outweighs testimony from Winn and Horne denying coordination, they wrote.

They also say Horne sent strategic information to Winn on Oct. 27 and requested that she attempt to raise an additional $100,000 for Business Leaders for Arizona, which Winn passed on to the consultant.

“Horne and Winn unambiguously coordinated on that day, and their acts also corroborate the circumstantial evidence that they coordinated on October 20, 2010,” deputy county attorney Benjamin Kreutzberg wrote.

One of the key witnesses against Horne was FBI agent Brian Grehoski, who testified that a witness told him by telephone that Horne didn’t consult with Winn on a real estate deal. The pair said their conversations were in part about that deal.

The witness recorded two of those calls, and they didn’t include those questions, and defense lawyers say he lied.

“Grehoski’s perjury is simply the latest in a long series of abuses that are emblematic of someone who is willing to pin a charge on the Defendants here,” La Sota wrote. “This Court should reject Agent Grehoski’s testimony in every respect.”

An FBI spokesman has said the agency’s Phoenix division stands “firmly behind” Grehoski.